Reconstruction of the Sector Structure of the Interplanetary Magnetic Field by Geomagnetic Station Data

Abstract—This paper describes a new method for reconstructing the polarity of the interplanetary magnetic field. The technique is based on the Svalgaard–Mansurov effect. We ause geomagnetic data of high-latitude stations with a long observation period, including the presatellite era. This method is designed to improve the quality and accuracy of reconstructed polarity, complementing the results of previous methods of Svalgaard (1975) and Vennerström et al. (2001). For the large presatellite period from 1926, the accuracy of the method is estimated to be around 89 % of overlaps with the interplanetary magnetic field polarity determined from satellite data. DOI: 10.1134/S001679321206014X 1

Was the unusual solar cycle at the end of the XVIII century a result of phase asynchronization?

Aims.The problem of the unusual sunspot cycle in 1784–1799 is considered. Why was the length of the 4th solar cycle exceptionally large? Was it really composed of two shorter cycles? Resolving this puzzle seems to be very important for modern dynamo theories trying to explain the solar cyclicity. Methods.We propose a possible scenario for the solar activity behavior during the 4th solar cycle. Analogies with the phase asynchronization observed at the time of the 20th solar cycle are presented. Results.We suggest that the length of the 4th solar cycle can be explained by outstanding phase asynchrony between Northern and Southern hemispheric activities reaching a delay up to 4.5 years. The main effect of such asynchronization results in strong North-South asymmetry during the course of the ascending phase of the solar cycle 4

Phase asynchrony of the north-south sunspot activity

Aims.Northern and Southern sunspot activities demonstrate striking synchronous behavior during a solar cycle. But sometimes synchronization fails and the north-south asymmetry occurs. The problem is the origin of the north-south asymmetry and its quasi-regular oscillations.Methods.We employed Cross-Recurrence Plot analysis to extract synchronization between the Northern and Southern sunspot activities.Results.By using Cross-Recurrence Plot technique and extracting line of synchronization we found that the north-south sunspot asymmetry is due to phase asynchrony between Northern and Southern hemispheric activities

Long-term asymmetry in the wings of the butterfly diagram

Aims. Sunspot distribution in the northern and southern solar hemispheres exibit striking synchronous behaviour on the scale of a Schwabe cycle. However, sometimes the bilateral symmetry of the Butterfly diagram relative to the solar equatorial plane breaks down. The investigation of this phenomenon is important to explaining the almost-periodic behaviour of solar cycles. Methods. We use cross-recurrence plots for the study of the time-varying phase asymmetry of the northern and southern hemisphere and compare our results with the latitudinal distribution of the sunspots. Results. We observe a long-term persistence of phase leading in one of the hemispheres, which lasts almost 4 solar cycles and probably corresponds to the Gleissberg cycle. Long-term variations in the hemispheric-leading do not demonstrate clear periodicity but are strongly anti-correlated with the long-term variations in the magnetic equator